| Object-based attention refers to two(or more)features belonging to same object are identified more quickly and more accurately than two(or more)features belonging to different object.Two-rectangle paradigm can study space-based and object-based attention,simultaneously,and has become one of the main paradigms for studying selective attention.Previous studies have shown that perceptual and semantic similarity can independently guide the attention allocation of geometric objects,that is,the object-based effect was larger in the dissimilar condition than in the similar condition.With the deepening of the research on object-based attention,more and more researchers use real objects instead of geometric objects to investigate the real object-based attention,and the real object is a combination of bottom-up perceptual properties and top-down semantic properties a "bottom-up" sensory attributes and a combination of top-down semantic properties.So far,there is no study to explore whether the perceptual and semantic similarity of real objects jointly or independently guides attentional allocation,and whether they have different mechanisms for the allocation of attention to real objects.The study included four experiments,used the variant of two-rectangle paradigm,to explore the question above.In Experiment 1,we randomly selected very faliliar objects frol the Internet that had shapes similar to a rectangle and conducted Likert 1-7 rankings of perceptual and semantic similarity of real objects.We selected four similarity conditions for the horizontal objects and four for the vertical objects:perceptually sinilar-semantically similar,perceptually similar-semantically dissimilar,perceptually dissimilar-senantically similar,and perceptually dissimilar-semantically dissimilar.In Experiment 2,we used the stimuli selected from Experiment 1 and aimed to explore the influence of object similarity on the real object-based attention.The results showed that the object-based effect was larger in the perceptually dissimilar condition than in the perceptually similar condition,there was no significant difference for object-based effect between semantically dissimilar and semantically similar conditions.The results indicated that perceptual similarity could independently guide the attentional allocation of real objects,however,semantic similarity could not independently guide the attentional allocation of real objects.In Experiment 3,we added a semantic priming task to folly activate the semantic information of real objects.The results showed that object-based effect was larger in the perceptually dissimilar condition than in the perceptually similar condition,moreover,object-based effect was larger in the semantically dissimilar condition than in the semantically similar condition.RTs were significantly faster in the perceptually similar-semantically dissimilar condition than in the perceptually similar-semantically similar condition for the invalid same-objects trials and RTs were significantly faster in the perceptually similar-semantically similar condition than in the perceptually dissimilar-semantically similar condition for the invalid different-objects trials.More importantly,RTs were significantly faster in the perceptually dissimilar-semantically dissimilar condition than in the perceptually similar-semantically similar condition for the invalid same-objects trials.The results indicated that perceptual and semantic similarity can independently guide attentional allocation to real objects.The mechanisms lunderlying them may differ,and the attentional system favors the semantic properties of real objects when both perceptual and semantic similarity play a role.In Experiment 4,we manipulated the SOA to explore the time course of the influence of object similarity on real object-based attention.The results showed that when the SOA was 250 ms,perceptual similarity could independently guide the attentional allocation of real objects,however,semantic similarity could not independently guide the attentional allocation of real objects;when the SOA was 750 ms5 perceptual and semantic similarity could independently guide the attentional allocation of real objects,respectively;when the SOA was 1250 ms,semantic similarity could independently guide the attentional allocation of real objects,perceptual similarity could not independently guide the attentional allocation of real objects.The results suggested that perceptual and semantic similarity could guide attentional allocation to real objects in different processing stages.Summing up all the results of four experiments of our study,the main following conclusions are drawn:(1)Perceptual and semantic similarity can independently guide attentional allocation to real objects and that the object-based effect of perceptual and semantic similarity may not be additive.(2)The mechanisms between perceptual and semantic similarity of attentional allocation on the real objects may differ.The reason why the object-based effect was larger in the perceptually dissimilar condition than in the perceptually similar condition was the slower response to invalid-different object trials in the perceptually dissimilar condition;however,The reason why the object-based effect was larger in the semantically dissimilar condition than in the semantically similar condition was the faster response to invalid-different object trials in the semantically dissimilar condition.(3)The real objects may depend on the semantic similarity to guide the attentional allocation.(4)Perceptual and semantic similarity could guide attentional allocation to real objects in different processing stages,namely that in the early stage of processing,perceptual similarity could guide attentional allocation to real objects,however,in the late stage of processing,semantic similarity could guide attentional allocation to real objects. |
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